Electromagnetic actuators are often used to control the injection of fuel into an internal combustion engine. In one example, fuel is delivered to the pumping chamber of a fuel injector, and a plunger piston (which may be moved in response to rotation of a cam arrangement) forces fuel from the pumping chamber. When an electrical solenoid within the fuel injector is activated, a control valve connecting the pumping chamber to a low-pressure tank is closed and fuel from the pumping chamber is forced toward the tip of the fuel injector, through a fuel nozzle, and subsequently into the combustion chamber of an engine. However, when the electrical solenoid is deactivated, the control valve remains open and fuel from the pumping chamber is forced into the low-pressure tank instead of being transmitted to the fuel nozzle and into the combustion chamber.
As shown in FIG. 1, an electromagnetic actuator as described above may include a stator 5 having an outer pole 5a and an inner pole 5b and may have a coil 7 disposed around the inner pole 5b between the inner pole 5b and the outer pole 5a. The stator 5 and coil 7 may be arranged within the bore of a stator housing 8. A high pressure fluid bore 9 may be formed through the housing 8 for transmission of fluid from the pumping chamber (not shown) toward the nozzle (not shown) of the fuel injector for subsequent injection into the combustion chamber of the engine.
Various improvements to electromagnetic actuators for controlling fluid flow have been made in the past. For example, various geometric configurations for inner and outer poles of a stator have been proposed with the intention of increasing pole area to thereby increase actuation force. However, as inner and outer pole dimensions are increased or modified, complex geometries for the stator and stator housing may be required—for example to (i) maintain desired product envelope dimensions, and/or (ii) insure that the high pressure fluid passageway 9 within the housing 8 is supported by sufficient high strength housing material for transmitting high pressure fluid through the housing 8 without rupture. Moreover, while various geometric configurations for inner and outer poles, coils, and stator housings have been proposed in the past, increased costs associated with producing such geometries may overcome other accomplished objectives.
Prior methods and devices for controlling fluid flow may be improved further by providing advanced actuator configurations that more effectively balance stator-coil force capacity, fluid passageway strength, and production cost and capability.
The present invention is directed at overcoming one or more disadvantages associated with prior devices and methods for controlling fluid flow through an electromagnetic actuator.